Brewing · Calculator

Brewing IBU Calculator

Enter your batch, boil gravity, and hop schedule to estimate bitterness in IBU with the Tinseth formula, plus BU:GU balance — live as you type.

Start calculating Read the guide
Hop pellets weighed beside hop cones and a brewing kettle

How to use this calculator

Estimate bitterness from your batch and hop schedule.

  1. 1

    Set batch conditions. Choose units, batch size and boil gravity.

  2. 2

    Add your hops. Enter the amount, alpha-acid percentage and boil time for each addition.

  3. 3

    Read the bitterness. Check each hop contribution, total IBU and the bitterness-to-gravity balance.

Use alpha-acid values from your hop packaging and the gravity during the boil. Results are model estimates.

Live calculator · Tinseth formula

Your batch & hops

Units
Hop additions
Amount (g) Alpha % Time (min) IBU
22.5
7.4
2.2

Uses the Tinseth model, the most common homebrew IBU estimate. Real bitterness varies with hop form, age, boil vigour, and whirlpool/dry-hop additions, which contribute little measured IBU.

Estimated bitterness

Total IBU 32
BU:GU ratio 0.64
BalanceBitter
Batch20.0 L
Malty → hoppy Bitter
See your hop schedule

What to do next

Hop this beer in 3 steps

For 20.0 L.

  1. 1

    Weigh the hops

    Before the boil

    30 g at 60 min, 20 g at 15 min, 15 g at 5 min.

  2. 2

    Add them on time

    60 min boil

    Count down from the start of the boil and add each charge at its time. Late additions give aroma, early ones bitterness.

  3. 3

    Check the balance

    Planning

    About 32 IBU at 1.050: a BU:GU of 0.64, bitter.

Free printable

Keep this batch on one page

A batch card made from your numbers, to save as a PDF or receive by email:

  • Your numbers in big type
  • These steps with tick-boxes
  • Brew, transfer and bottling dates
  • A brew log for every reading

Optional. You can get your PDF without subscribing. Privacy notice.

Typical IBU by beer style

StyleTypical IBUCharacter
Light lager8–18Clean, low bitterness
Pale ale30–45Noticeable hop balance
IPA40–70Firmly bitter
Double IPA60–100Aggressively hoppy
Stout / porter25–45Roast balances bitterness
Wheat / hefeweizen8–15Soft, low bitterness

IBU guide

Dial in the bitterness.

Bitterness comes from when and how much you hop, tempered by your boil gravity. This guide explains the Tinseth model and how to hit a style's target range.

Longer boils bitter far more — edit the schedule live below .

How we calculate: Brewing methods

Use these reference values to interpret your results

  • Model

    Tinseth

    The most common homebrew utilisation model.

  • Balanced

    0.5

    A BU:GU ratio around here tastes balanced.

  • Most bitterness

    60 min

    The long boil addition does most of the work.

Tinseth

IBU = util × (AA × g × 1000 / L)

Utilisation rises with boil time and falls with boil gravity, so long, low-gravity boils extract the most bitterness from a given weight of hops.

The Tinseth formula behind the tool

For each addition, Tinseth multiplies the alpha acid concentration in the wort by a utilisation factor. That factor combines a bigness term — lower for denser wort — and a time term that rises quickly over the first 30 minutes of the boil and then flattens.

This is why a 60-minute addition contributes far more bitterness than a 10-minute one of the same weight, and why identical hops bitter a light beer more than a strong one. The calculator applies all of this automatically per addition.

Understand and use your results

Set your units, batch size, and boil gravity, then enter each hop addition — amount, alpha acid percentage, and boil time. The calculator returns the IBU each addition contributes and the total, updating live as you adjust any field.

Enter the alpha acid figure from your hop packaging, since it varies by harvest. Use your boil gravity rather than the finished original gravity if you dilute afterward, because bitterness extraction happens during the boil.

What an IBU actually measures

An IBU is roughly one milligram of isomerised alpha acid per litre of beer. Alpha acids come from hops and only become bitter once heat isomerises them during the boil. The longer and hotter the boil, the more isomerisation, and the higher the IBU.

Measured bitterness is not the same as perceived bitterness. A malty, high-gravity beer can carry 60 IBU and taste balanced, while a dry pale ale at 35 IBU can taste sharply bitter. IBU is the objective anchor; balance comes from context.

Balancing with BU:GU

The BU:GU ratio divides bitterness units by gravity units to judge balance before you brew. It is a fast sanity check that a recipe will not taste thin and harsh or cloying and flat.

Aim for the balance your style wants: malty beers sit low, hoppy beers sit high. Adjust hop timing and weight to move the ratio without changing the whole grain bill.

Under 0.4Malty — sweetness leads.
0.4–0.6Balanced — the everyday target.
0.6–0.8Bitter — hops lead.
Over 0.8Very hoppy — IPA territory.

Typical IBU by style

Light lagers and wheat beers sit low, around 8 to 18 IBU, letting malt and yeast character lead. Pale ales land 30 to 45, IPAs 40 to 70, and double IPAs can push past 100, where perceived bitterness plateaus even as the number climbs.

Dark beers like stouts and porters often measure 25 to 45 IBU, but roast bitterness from the malt adds to the impression, so they can taste more bitter than the number suggests. Use the chart in the calculator to aim for your style.

FAQ

IBU questions

Common questions about bitterness, hop utilisation, and balance.

What is an IBU?
IBU stands for International Bitterness Unit, a measure of the concentration of isomerised alpha acids — the compounds from hops that taste bitter — in finished beer. One IBU is roughly one milligram of isomerised alpha acid per litre. Higher IBU means more measured bitterness, though perceived bitterness also depends on malt sweetness.
How does this IBU calculator work?
It uses the Tinseth formula, the most widely used homebrew model. For each hop addition it multiplies the alpha acid concentration by a utilisation factor that depends on boil gravity and boil time, then sums the additions. Longer boils and lower gravity extract more bitterness, which the formula captures.
Why does boil gravity affect IBU?
Denser, sugar-rich wort extracts alpha acids less efficiently, so the same hops in a higher-gravity boil yield fewer IBU. That is why big beers need proportionally more hops for the same bitterness. Enter your boil gravity — not your original gravity if you top up afterward — for the most accurate estimate.
What is the BU:GU ratio?
BU:GU compares bitterness units to gravity units (the last two digits of gravity). It gauges balance: around 0.5 is balanced, below 0.4 leans malty, and above 0.7 is firmly bitter. It is a quick way to judge whether a recipe will taste balanced before you brew it.
Do whirlpool and dry hops add IBU?
Very little measured IBU. Hops added at flameout, in the whirlpool, or as dry hops contribute aroma and flavour but isomerise few alpha acids, so this calculator focuses on boil additions. Late and dry hops still shape perceived bitterness even though the IBU number barely moves.
How accurate is the estimate?
Tinseth is a solid planning estimate, not a lab measurement. Real IBU shifts with hop form and freshness, boil vigour, wort pH, and how you handle late additions. Use it to compare recipes and hit a target range rather than to predict an exact laboratory value.

Continue with the next calculator

Calculators and guides for your next step.

Ads.txt